DNS

The Domain Name System translates names such as example.com into records that computers can use.

Simplified resolution process

1. The application asks the operating system for a name.
2. A configured resolver checks its cache.
3. If necessary, recursive DNS infrastructure queries authoritative servers.
4. The answer is returned and cached for its time-to-live period.

Important record types

• A maps a name to an IPv4 address.
• AAAA maps a name to an IPv6 address.
• CNAME creates an alias.
• MX identifies mail servers.
• TXT stores text used for verification and policies.

Useful lab commands include nslookup, dig and host. DNS data can support troubleshooting and defensive investigation, but it should not be treated as proof that a service is safe.